Vibrating screen devices and vibrating feeder devices are generally well known in the art. On a typical vibrating screening device, a system of classifying screens are mounted to a frame which in turn is supported on a system of springs. At or near the center of the device is an eccentrically weighted shaft unit, typically having one, two, or three or more rotating and eccentrically weighted shafts. On a multi-shaft unit, the shafts may be counter-rotating such that the eccentric weights are oriented in the same direction twice each revolution. This causes the screen to vibrate, which aids the classifying effects of the screen device. On a vibrating feeder, a similar shaft unit vibrates the feed trough or chute, which "throws" the aggregate contained in the trough in a desired direction. An example of such a device can be found in U.S. Pat. No. 4,340,469 issued to Archer.
The ends of the rotating shafts are supported by bearings, and the shafts are operatively coupled to a drive motor. Each shaft includes a gear or drive wheel. The eccentric weights are typically attached directly to the drive wheel.
The bearings and the gear teeth on the drive wheels require constant lubrication, and thus such components are disposed within a housing or wheel case containing a quantity of oil or other suitable lubricating fluid. A wheel case is typically provided on each side of the vibratory device, with each wheel case typically being bolted to an adjacent sidewall or a portion of the frame of the vibratory device.
Proper lubrication of the wheel case, and proper cooling of the lubricant, is a continuing problem. Typically, the oil level inside the wheel case is near the lowest point of travel of the wheel (bottom dead center). The oil level is maintained such that the weights attached to the rotating wheel dip strike the oil and "splash" the oil upward, thereby splashing oil onto the bearings. The gear teeth on the outer circumference of the wheel, which has a swing diameter slightly greater than the swing diameter of the rotating weights, dip slightly deeper into the oil level, thus lubricating the outer portions (i.e., the gear teeth) of the wheel.
In practice, it has been discovered that the temperature of the oil is very dependent on the how far the rotating weights dip into the oil. If the oil level is increased so that the weights dip further into the oil, the operating temperature of the oil rises, as does the operating temperature of the various components, especially the bearings. Accordingly, to keep the oil temperature down conventional practice has been to maintain the oil at a sufficiently low level so that only the gear teeth, but not the weights, actually dip into the oil. In practice, the oil is agitated by the gear teeth on the rotating wheels, and the oil is further agitated by the resulting vibration of the vibratory device. The rotating weights contact the agitated oil and distribute the oil to the bearings.
Unfortunately, in practice there is a significant lag time between the initial start-up of the vibratory device and the time the oil is warm enough and agitated enough to be properly distributed by the rotating weights. This lag time is exaggerated by low ambient temperatures when the oil is significantly more viscous. During this lag time the bearings are starved of lubricant, which leads to premature bearing failure.
Another problem in conventional wheel cases is that the action of the rotating wheels and the attached weights tend to shift the oil within the housing, creating areas of oil accumulation and areas of oil depletion. The areas of oil depletion decrease the amount of oil available for distribution to the bearings, leading to bearing failure. This problem is accentuated in two-shaft and three-shaft units.
Accordingly, the present invention is directed to an improved wheel case having an improved lubrication system. This improved lubrication system for a wheel case fosters better distribution and cooling of the lubricant and serves to extend the useful life span of the rotating components housed within the wheel case.